Generally, it is desirable to be able to control internal combustion engine torque during vehicle operation. Various reasons exist for reducing the amount of engine (brake) torque generated. For example, there may be a need for a reduction of engine torque for traction control or anti-spin control purposes. Furthermore, engine torque may need to be reduced in order to protect certain vehicle components.
In addition to being able to determine how much engine torque should be reduced, it is also desirable to identify and implement the appropriate control actions required to reduce the torque to the desired torque in an acceptable period of time. For example, controlling the amount of air delivered to the engine for combustion purposes is generally a slower process than controlling spark advance. Although existing strategies have utilized spark retard and/or cylinder cutoff to reduce torque, the prior art has yet to teach the coordinated control of the present invention.
There is, therefore, a need to develop a strategy for controlling the amount of net engine torque produced by an internal combustion engine utilizing coordinated torque reduction control operations.